The discussion below is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.
Aspects of the invention relate to a mooring assembly for a vessel, comprising a receiving vessel part, a geostationary part received rotatably in said receiving vessel part and a main bearing assembly connecting the geostationary part to the receiving vessel part.
As known generally, such a mooring assembly allows a vessel to weathervane around a geostationary part (e.g. turret). The main bearing assembly transfers the main loads from the geostationary part towards the receiving vessel part and thus towards the vessel, and vice versa, while allowing the rotation between the geostationary part and the vessel.
It is noted, that, sometimes, such a mooring assembly also may comprise additional, auxiliary bearing assemblies which, however, are intended to transfer only a part of the (main) loads between the vessel and the geostationary part. Aspects of the present invention are directed to the main bearing assembly which, essentially, transfers almost the entire load between the vessel and geostationary part.
The main bearing assembly in such a mooring assembly often is a critical item. Therefore a very high reliability of the main bearing assembly is essential. Typically a roller bearing is used as main bearing for its proven reliability. Nowadays, when such a main bearing assembly, or critical parts thereof, are damaged and should be replaced or repaired, complicated operations are needed, amongst which transferring the combination of vessel and geostationary part, after disconnecting the mooring lines, to another location, for example in sheltered water or a shipyard. However, such operations are highly undesirable, basically because of the very costly loss of production time (such a mooring assembly primarily is used at a production location, for example at an offshore oil field or gas field). Alternatively, the geostationary part may be supported temporarily on station by auxiliary devices, but this most likely will severely hinder or completely prevent weathervaning of the vessel during repair/overhaul/replacement of the main bearing.